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Old 11-11-2006, 05:56 PM
crusherdbuzz's Avatar
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383 Rod & Cam clearance

Today while at engine class, a friend of mine was putting together his 383 and had problems with the rod hitting the cam. I am worried I may have similiar problems. I am running as follows:
-Eagle Cast 383 crank
-Scat I Beam Forged 5.7 Rods w/ ARP
-probe flat top forged pistons
-comp cams XE274 cam (I got it ground with a small base circle). Cam specs are 230/236 @ 50 with .490/.490 lift.

He is using the same crank and rods I am; however, he is using a crane cam that wasn't ground on a small base circle. What got me is the cam he is using is only .465 lift. This got me worrying. I've seen a few build up articles using the same if not bigger cam I am and I don't remember reading any clearencing issues other than the oil pan rails. Am I going to potentially have this problem as well? He is going to skim the bolt side of the rods to get it to clear. I am hoping the cam I have won't have this problem. I've already clearanced the block for the rod bolts.

Regards,
Dennis
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Old 11-11-2006, 06:38 PM
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The cam to rod clearance is something you need to check real close. My machist told me about it when I picked up my motor, ready to be assembled. I didnt have any problems but he said if there was a clearance issue to just what your friend is doing. He does lots of high performance work around my area and has a super reputation. I think it is more to do with the centering of the cam in the block. they are all not exactly centered, and some need the rod caps ground a little and some dont.
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Old 11-11-2006, 08:01 PM
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Every block is different. I grind the inner rod bolt head on all 383 and 406 with 5.7 GM rods. Not much has to be removed. Easily done with a common bench grinder. Not all rods will hit. Usually one or two. Grinding all keeps the balance better.
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Old 11-11-2006, 08:41 PM
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I've already had the assembly balanced. After I figure if I need to grind the rod bolts or not, do I need to get it balanced again?
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Old 11-11-2006, 08:43 PM
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if you run into this at assembly (with the rotating assembly already balanced) and then grind on rod cap bolts or rod caps does this throw it outa balance ? or not enough to worry about ?



just curious cause you spend the money to balance.





Mustangsaly
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Old 11-11-2006, 09:00 PM
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Not enough is removed to bother the balance.
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Old 11-11-2006, 09:02 PM
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Thnx bob you put my mind at rest lol .
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Old 11-12-2006, 11:25 AM
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So if I use standard facotry rods with ARP bolts and a 383 crank with a standard base circle cam, can I make it fit with just a little grinding on the rod bolt caps?
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Old 11-12-2006, 06:05 PM
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ARP now makes special rod bolts for this application. The part number is 134-6027. They have a larger chamfer on the head for camshaft clearance. It's too late to use this info on your engine, but hopefully it will help others who are getting ready to build a 383.

Barry
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Old 11-12-2006, 06:17 PM
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thanks topfuel,




good info











Mustangsaly
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